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Biomedical subjects

D J Purdell-Lewis

Publications and source records attributed to D J Purdell-Lewis.

At least 19 recordsLinked to original sources
PubMed1989

[Decision making analysis and the diagnosis of approximal caries].

A decision tree approach to dental caries diagnosis has been described, using information obtained from the literature on caries prevalence and on the accuracy of dentists when using a mirror and probe or bitewing radiographs for diagnosing doubtful approximal carious lesions. In this example, three different diagnostic pathways are compared with the pathway 'no dental examination'. The expected value of clinical information was calculated for the three pathways as were the predictive values, positive and negative, for the various test combinations. In a sensitivity analysis the caries prevalence and diagnostic accuracy were varied for the above calculations within realistic levels. Extrapolations from the results indicated that the procedure 'probe and look' is counter productive at low caries prevalence, since, for all pathways, diagnosing 'sound' surfaces as having dentine caries becomes an increasing problem. This decision making approach highlights the fact that more information on the diagnostic process is needed before recommendations about changing diagnostic criteria, pathways or techniques are made. In particular the diagnostic accuracy of dentists using radiographs and especially the weighting they put on different diagnostic outcomes should be investigated.

Decision Support Techniques↗
PubMed1988

Long term results of chemotherapy on the developing dentition: caries risk and developmental aspects.

The dental health of 45 children who had been placed on long term evaluation after chemotherapy treatment for malignancies was examined in this study. All children had received cytotoxic drugs during the period of tooth formation. It was found that they had more filled or diseased permanent teeth than control children. Their current caries activity as indicated by initial white spot lesions was also higher. Forty-three of the children showed evidence of disturbed amelogenesis. This had resulted in aesthetically displeasing grooves, pits and discoloration. Twenty-three of the children were counseled on the possibility of cosmetic dentistry. Delayed eruption and shortened, malformed roots were also found on several patients. It was concluded that these patients constitute a high risk dental care group.

Adolescent↗
PubMed1988

Monobacterial and mixed bacterial plaques of Streptococcus mutans and Veillonella alcalescens in an artificial mouth: development, metabolism, and effect on human dental enamel.

To gain greater understanding of the role of Streptococcus mutans and Veillonella in the caries process, studies of both aerobically and anaerobically grown plaques of S. mutans C67-1 and V. alcalescens V-1 on human enamel slabs were carried out in an artificial mouth. Plaque development, acid production, and demineralization were measured. Early plaque development of monobacterial and mixed bacterial plaques started from randomly adhering cells on day 1 to confluent multilayered microcolonies on day 4. Differences were observed in viable cell counts, total cell mass, and in acid production. In most cases CFU, DNA and acid production were higher in the mixed bacterial plaque, especially in the anaerobic mixed plaque. Lactic acid was the predominant acid in all cases following the supply of sucrose to the plaque. No decisive role could be found for acetic, formic, and propionic acid. No inhibition of demineralization was observed in the enamel slabs inoculated with both aerobic and anaerobic mixed plaques. Demineralization ranged from the more classical picture of lesion development in the aerobic monobacterial plaque-treated samples to an aggressive etching of the enamel surface in the anaerobically mixed treated slabs.

Aerobiosis↗
PubMed1987

[The dentin].

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Dental Pulp Diseases↗
PubMed1987

Artificially induced developmental defects in sheep enamel examined by scanning electron microscopy.

Upper incisor teeth from sheep infected with parasites or given 6 mg fluoride per kg bodyweight for 21 days during the period of tooth formation were examined with SEM and microradiography. It was found using both techniques that there had been a severe disturbance of the secretory ameloblasts leading to enamel hypoplasia. It is suggested that it is the severity rather than the cause of the insult to the ameloblasts which determines the degree of hypoplasia.

Ameloblasts↗
PubMed1986

Estimation of alveolar crest height using routine periapical dental radiographs.

The reproducibility of estimations of the alveolar crest height based on their relationship to two other fixed points on the tooth has been analyzed in a study of 302 routine periapical radiographs of 96 endodontically treated teeth. The radiographs were made at normal recall appointments by use of the extension tube paralleling technique. The various distances between four fixed points on each tooth in any radiographic series were compared by means of a statistical model. The results indicate that, in periodontal follow-up studies, completely standardized projection of the structures onto the film is unnecessary since measurements of the crest height can be related to any suitable fixed measuring standard on the tooth.

Alveolar Process↗